Non-axisymmetric endwall structure based on a spline surface, compressor blade and application

Abstract

The present disclosure relates to the field of compressor aerodynamic design, in particular to a non-axisymmetric endwall structure based on a spline surface, a compressor blade and an application, the modeling range of the non-axisymmetric endwall structure covers an area from 25% of the axial chord length upstream of the blade leading edge to 25% of the axial chord length downstream of the trailing edge in the axial direction, the axial chord length is the axial distance between the blade leading edge and the trailing edge; the endwall profile is lofted by 6 tangential control lines, wherein each tangential control line is a cubic spline curve with a tangential width equal to the grid spacing determined by 6 points; the endwall profile lofted by the 6 tangential control lines includes a pit near the suction surface of the front section of the blade passage and a double-peak bulge of the rear section of the blade passage in geometric characteristics. The present disclosure aims to improve the flow in the end region of the compressor blade.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the field of compressor aerodynamic design, and in particular to a non-axisymmetric endwall structure based on a spline surface, a compressor blade and application. BACKGROUND

[0002] Modern aviation compressor aerodynamic design no longer pursues the ability to improve the stage load capacity of energy conversion alone, but needs to coordinate the contradictions between high load, high throughflow, high efficiency and surge margin in the whole operating range. A big difficulty in high load compressor design is that highly three-dimensional flow is difficult to control, and the problem of secondary flow and flow separation is very serious. The flow loss caused by secondary flow can account for 30%-50% of the total aerodynamic loss of the blade row.

[0003] However, three-dimensional separation of the compressor not only causes a sharp increase in flow loss, but also can cause the inlet flow environment of the downstream blade row to deteriorate, and even can induce rotating stall. As can be seen, secondary flow and three-dimensional separation have become one of the key factors restricting the performance improvement of modern aviation compressors, and flow control has become the focus that needs to be broken through in compressor aerodynamic design. SUMMARY

[0004] To solve the above problems mentioned in the background, the present disclosure provides a non-axisymmetric endwall structure based on a spline surface, a compressor blade and application, aiming to improve the flow in the end region of the compressor blade.

[0005] According to an aspect of the present disclosure, a non-axisymmetric endwall structure based on a spline surface is provided, the modeling range of the non-axisymmetric endwall structure covers the region from 25% of the axial chord length upstream of the blade leading edge to 25% of the axial chord length downstream of the trailing edge in the axial direction, the axial chord length being the axial distance between the blade leading edge and the trailing edge; the endwall profile is lofted by 6 tangential control lines, wherein each tangential control line is a cubic spline curve with a tangential width equal to the grid spacing determined by 6 points; the endwall profile lofted by the 6 tangential control lines includes a pit near the suction surface of the front section of the blade passage and a double-peak bulge of the rear section of the blade passage in geometric characteristics.

[0006] Optionally, the 6 tangential control lines include a first tangential control line to a sixth tangential control line, the first tangential control line and the sixth tangential control line respectively determine the axial boundaries of the endwall profile, and the second tangential control line to the fifth tangential control line are distributed equidistantly between the leading edge and the trailing edge.

[0007] Optionally, the line connecting the same side end points of the first tangential control line and the second tangential control line is tangent to the mean camber line at the leading edge; the line connecting the same side end points of the fifth tangential control line and the sixth tangential control line is tangent to the mean camber line of the blade at the trailing edge; the two fixed points on the second tangential control line to the two ends of the fifth tangential control line are connected to the mean camber lines of two adjacent blades respectively, and the tangential distance between the two adjacent points on each control line is equal, and is equal to one fifth of the pitch distance, wherein the pitch distance is the tangential distance between the leading edges of the two adjacent blades.

[0008] Optionally, the spanwise coordinates of the first tangential control line and the sixth tangential control line are both 0, forming a straight line with a spanwise coordinate equal to 0.

[0009] Optionally, the second tangential control line to the fifth tangential control line is determined by the fixed points with a spanwise coordinate equal to 0 at both ends and four control points in the middle.

[0010] Optionally, the relative spanwise coordinates of the four control points in the middle of the second tangential control line to the fifth tangential control line are as follows: the relative spanwise coordinates of the points on the second tangential control line are -0.0065, -0.0266, -0.0430 and -0.0434 respectively; the relative spanwise coordinates of the points on the third tangential control line are -0.0033, -0.0290, -0.0692 and -0.0360 respectively; the relative spanwise coordinates of the points on the fourth tangential control line are 0.0185, 0.0245, -0.0186 and -0.0193 respectively; the relative spanwise coordinates of the points on the fifth tangential control line are 0.0022, 0.0168, 0.0353 and 0.0204 respectively; wherein the relative spanwise coordinate is defined as the ratio of the spanwise coordinate value to the chord length of the blade.

[0011] According to another aspect of the present disclosure, a compressor blade with the spline surface-based non-axisymmetric end wall structure is provided.

[0012] According to another aspect of the present disclosure, an application of the compressor blade to an aero-engine is provided.

[0013] Compared with the prior art, the present disclosure has the following beneficial effects:

[0014] 1) The present disclosure can reduce the total pressure loss of airflow through the blade passage by inhibiting the corner separation in the end region of the compressor blade;

[0015] 2) The present disclosure can avoid stall at high angle of attack by weakening the corner separation of the compressor at high angle of attack, thereby expanding the available angle of attack range of the compressor blade.

[0016] 3) The precise design of the endwall profile and the layout of the control lines in the present disclosure significantly improve the flow in the end region of the compressor blade, which optimizes the aerodynamic performance of the compressor, including increasing the flow rate, reducing noise, etc., thereby improving the overall performance.

[0017] 4) The non-axisymmetric endwall structure in the present disclosure expands the available angle of attack range, so that the compressor can adapt to more variable operating conditions. This adaptability improves the compressor to maintain high efficiency and stable operation in a wider operating range, enhancing its flexibility and reliability in practical applications.

[0018] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, but not limiting the present disclosure.

[0019] Other features and aspects of the present disclosure will become apparent from the following detailed description of exemplary embodiments with reference to the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0020] The drawings incorporated in and constituting a part of the specification illustrate embodiments consistent with the present disclosure and, together with the description, serve to explain the principles of the present disclosure.

[0021] Figure 1 A non-axisymmetric endwall parameterization diagram in the embodiment of the present disclosure is shown;

[0022] Figure 2 A non-axisymmetric endwall contour plot in the example of the present disclosure is shown;

[0023] Figure 3 A compressor blade with a non-axisymmetric endwall in the embodiment of the present disclosure is shown;

[0024] Figure 4 A total pressure loss coefficient versus angle of attack plot of a prototype cascade and a non-axisymmetric endwall cascade in the embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0025] Various exemplary embodiments, features and aspects of the present disclosure will be described in detail below with reference to the accompanying drawings. The same reference numbers in the drawings represent functionally the same or similar elements. Although various aspects of the embodiments are shown in the drawings, the drawings are not necessarily drawn to scale unless specifically indicated.

[0026] The word "exemplary" is used herein in the sense of being an example, illustration, or demonstration. Any embodiment described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments.

[0027] In addition, in order to better illustrate the embodiments in the present disclosure, numerous specific details are given in the following specific embodiments. It should be understood by those skilled in the art that the present disclosure can also be implemented without certain specific details. In some examples, methods, means, elements and circuits well known to those skilled in the art are not described in detail in order to highlight the main ideas of the present disclosure.

[0028] In order to make the purpose, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions in the embodiments of the present disclosure will be described clearly and completely in the following with reference to the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present disclosure.

[0029] The embodiments of the present disclosure provide a non-axisymmetric endwall structure based on a spline surface, which comprises an endwall profile formed by 6 tangential control lines, wherein each control line is a cubic spline curve with a tangential width equal to a grid spacing determined by 6 points. The blade parameters are shown in Table 1:

[0030] Table 1 Blade parameters

[0031]

[0032] In an embodiment, as shown in Figure 1 , a non-axisymmetric endwall parameterization schematic diagram is shown, and the modeling range covers the area from 25% axial chord upstream of the blade leading edge to 25% axial chord downstream of the trailing edge in the axial direction. The endwall profile is obtained by lofting 6 tangential control lines, and each tangential control line is a cubic spline curve determined by 6 points. Among them, the axial position of the first tangential control line (L1 in Figure 1 ) is at 25% axial chord upstream of the blade leading edge, the axial position of the second tangential control line (L2 in Figure 1 ) is at the blade leading edge, the axial positions of the third tangential control line (L3 in Figure 1 ) and the fourth tangential control line (L4 in Figure 1 ) are at 33% and 67% axial chord downstream of the blade leading edge respectively, the axial position of the fifth tangential control line (L5 in Figure 1 ) is at the blade trailing edge, and the axial position of the sixth tangential control line (L6 in Figure 1 ) is at 25% axial chord downstream of the blade trailing edge.

[0033] In one embodiment, the geometry of the endwall profile includes a concave pit near the suction surface of the leading section of the blade passage and a bimodal convex bump at the trailing section of the blade passage, which can reduce the total pressure loss of the airflow through the blade passage by suppressing the corner separation at the end region of the compressor blade.

[0034] In one embodiment, the line connecting the same side end points of the first tangential control line and the second tangential control line is tangent to the camber line at the leading edge; the line connecting the same side end points of the fifth tangential control line and the sixth tangential control line is tangent to the camber line at the trailing edge of the blade; the two fixed points on the second tangential control line to the two ends of the fifth tangential control line are connected to the camber lines of two adjacent blades respectively, and the tangential distance between the two adjacent points on each control line is equal, which is equal to one fifth of the pitch distance, wherein the pitch distance is the tangential distance between the leading edges of the two adjacent blades.

[0035] In one embodiment, the spanwise coordinates of the first tangential control line and the sixth tangential control line are both 0, forming a straight line with spanwise coordinate equal to 0. The second tangential control line to the fifth tangential control line is determined by the two fixed points with spanwise coordinate equal to 0 at the two ends and four control points in the middle.

[0036] In one embodiment, the relative spanwise coordinates of the four control points in the middle of the second tangential control line to the fifth tangential control line are as follows: the relative spanwise coordinates of the points on the second tangential control line are -0.0065, -0.0266, -0.0430 and -0.0434 respectively; the relative spanwise coordinates of the points on the third tangential control line are -0.0033, -0.0290, -0.0692 and -0.0360 respectively; the relative spanwise coordinates of the points on the fourth tangential control line are 0.0185, 0.0245, -0.0186 and -0.0193 respectively; the relative spanwise coordinates of the points on the fifth tangential control line are 0.0022, 0.0168, 0.0353 and 0.0204 respectively; wherein the relative spanwise coordinate is defined as the ratio of the spanwise coordinate value to the blade chord length. As shown in Table 2, the relative spanwise coordinates of each point on the tangential control lines L2 to L5 are given, wherein the name of each point is the name of the tangential control line to which it belongs plus the point serial number, for example, the second point on the second tangential control line L2 is called L22. The relative spanwise coordinates in Table 2 are defined as the ratio of the spanwise coordinate value to the blade chord length. Figure 1

[0037] Table 2 Relative spanwise coordinates of points on tangential control lines

[0038]

[0039] The non-axisymmetric endwall profile shown in Figure 2 is obtained by lofting the above six tangential control lines.

[0040] ​The embodiment of the present disclosure also provides a compressor blade comprising the non-axisymmetric end wall structure based on the spline surface in the above embodiment, such as Figure 3 Fig. 4 shows the compressor blade with the non-axisymmetric end wall in the embodiment.

[0041] wherein, Figure 4 The variation trend of the total pressure loss coefficient of the prototype cascade and the non-axisymmetric end wall cascade with the angle of attack is given. The non-axisymmetric end wall reduces the total pressure loss of the compressor cascade at the angle of attack of negative 4 to positive 6 degrees. At the angle of attack of positive 6 degrees, the non-axisymmetric end wall reduces the total pressure loss of the prototype cascade in the stall state to the total pressure loss in the non-stall state by weakening the compressor corner separation, and the loss reduction reaches 47%.

[0042] Through the above analysis, it can be known that the compressor blade in the embodiment of the present disclosure can achieve good effects when applied to an aero-engine, that is, the stall at large angle of attack working condition can be avoided by weakening the compressor corner separation at large angle of attack working condition, so as to expand the available angle of attack range of the compressor blade.

[0043] The flow diagrams and the block diagrams in the drawings are presented to illustrate the architecture, functionality, and operations of possible implementations of systems, methods, and computer program products according to various embodiments of the present disclosure. In this regard, each block in the flow diagrams and the block diagrams can represent a module, a segment, or a portion of code, which comprises one or more executable instructions for implementing the specified logical functions. In some alternative implementations, the functions noted in the blocks can occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently or in the reverse order, depending on the functionality involved. It is also noted that each block in the block diagrams and / or flow diagrams, and combinations of blocks in the block diagrams and / or flow diagrams, can be implemented by dedicated hardware-based systems that perform the specified functions or acts, or can be implemented by a combination of dedicated hardware and computer instructions.

[0044] The embodiments of the present disclosure have been described above, and the above description is exemplary and is not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The selection of the terms used herein is intended to best explain the principles, practical applications, or technical improvements of the technology in the market, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A non-axisymmetric end-wall structure based on spline surfaces, characterized in that, The non-axisymmetric endwall structure's shape range covers an area axially extending from 25% of the axial chord length upstream of the blade's leading edge to 25% of the axial chord length downstream of the trailing edge, where the axial chord length is the axial distance between the blade's leading and trailing edges. The endwall profile is obtained by lofting six tangential control lines, where each tangential control line is a cubic spline curve with a tangential width equal to the grid pitch, determined by six points. The endwall profile obtained by lofting the six tangential control lines includes, geometrically, a recess near the suction surface at the leading end of the blade channel and a double-peaked convex hull at the trailing end of the blade channel. The six tangential control lines include the first tangential control line to the sixth tangential control line. The first tangential control line and the sixth tangential control line respectively determine the axial boundary of the end wall profile. The second tangential control line to the fifth tangential control line are equidistantly distributed between the leading edge and the trailing edge. The relative spanwise coordinates of the four control points between the second and fifth tangential control lines are as follows: The relative spanwise coordinates of the points on the second tangential control line are -0.0065, -0.0266, -0.0430, and -0.0434; the relative spanwise coordinates of the points on the third tangential control line are -0.0033, -0.0290, -0.0692, and -0.0360; the relative spanwise coordinates of the points on the fourth tangential control line are 0.0185, 0.0245, -0.0186, and -0.0193; and the relative spanwise coordinates of the points on the fifth tangential control line are 0.0022, 0.0168, 0.0353, and 0.0204. The relative spanwise coordinate is defined as the ratio of the spanwise coordinate value to the blade chord length.

2. The non-axisymmetric end-wall structure based on spline surface according to claim 1, characterized in that, The line connecting the endpoints of the first and second tangential control lines on the same side is tangent to the mid-arc line at the leading edge; the line connecting the endpoints of the fifth and sixth tangential control lines on the same side is tangent to the mid-arc line at the trailing edge of the blade; the two fixed points at both ends of the second and fifth tangential control lines are respectively connected to the mid-arc lines of two adjacent blades, and the tangential distance between two adjacent points on each control line is equal, which is equal to one-fifth of the grid pitch, wherein the grid pitch is the tangential distance between the leading edges of two adjacent blades.

3. The non-axisymmetric end-wall structure based on spline surface according to claim 1, characterized in that, The span coordinates of the first and sixth tangential control lines are both 0, forming a straight line with a span coordinate of 0.

4. The non-axisymmetric end-wall structure based on spline surface according to claim 1, characterized in that, The second to fifth tangential control lines are determined by fixed points at both ends with span coordinates equal to 0 and four control points in the middle.

5. A compressor blade, characterized in that, It has a non-axisymmetric endwall structure based on spline surface as described in any one of claims 1-4.

6. An application of the compressor blade as described in claim 5 in an aero engine.

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